The present invention relates to the field of communications, and, more particularly, to phased array antennas and related methods.
Antenna systems are widely used in both ground based applications (e.g., cellular antennas) and airborne applications (e.g., airplane or satellite antennas). For example, so-called xe2x80x9csmartxe2x80x9d antenna systems, such as adaptive or phased array antennas, combine the outputs of multiple antenna elements with signal processing capabilities to transmit and/or receive communications signals (e.g., microwave signals, RF signals, etc.). As a result, such antenna systems can vary the transmission and/or reception pattern of the communications signals in response to the signal environment to improve performance characteristics.
For example, each antenna element typically has a respective phase shifter and/or attenuator associated therewith. The phase shifters/attenuators may be controlled by a central controller, for example, to adjust respective phases/attenuations of the antenna elements across the array. Thus, it is possible to perform beam shaping or to adjust beam width (i.e., (xe2x80x9cspoilingxe2x80x9d) to receive or transmit over a wider area.
To accomplish such beam shaping or spoiling for example, the central controller of a typical prior art phased array antenna may compute (or look up from a table) a new phase shifter and/or attenuator control value for each antenna elements for each successive beam shape to be implemented across the array. These values would then be communicated to the respective antenna elements to implement the new beam shape. Unfortunately, this approach generally requires that the central controller must look up element specific position data for each element and calculate the spoiling data for each element, which can be a relatively slow process. The central controller would then transmit the corresponding data to each element. As a result, the resulting delays of implementing a new beam shape may cause appreciable and undesirable signal outages, for example.
An example of a prior art control architecture for a phased array antenna is disclosed in U.S. Pat. No. 4,980,691 to Rigg et al. This patent is directed to a distributed parallel processing architecture for electronically steerable multi-element radio frequency (RF) antennas. The array is subdivided into several sub-arrays, where each sub-array has more than one RF radiating element, and a phase shift interface electronics (xe2x80x9cPIExe2x80x9d) device for each sub-array. Parameters specific to the RF elements within each sub-array are preloaded into the corresponding PIE. Pointing angle and rotational orientation parameters are broadcast to the PIEs which then calculate, in parallel and in a distributed processing manner, the phase shifts associated with the various elements in the corresponding sub-arrays.
While such prior art approaches may provide some improvement in the time required to change a beam shape, they may still be limited in their ability to provide sufficiently small beam shape changing times in certain applications. That is, while all of the spoiling data is not calculated by the central controller for each antenna element, each of the sub-array phase shift interfaces must still perform such calculations for all of its respective sub-array antenna elements. Thus, beam shape changing times may still be appreciably large when many antenna elements are included within a sub-array. This problem may be further compounded when relatively complex beam shapes are being implemented, which may require a fairly large amount of computation for each antenna element.
In view of the foregoing background, it is therefore an object of the present invention to provide a phased array antenna and related method which provides for relatively rapid beam shape changing.
This and other objects, features, and advantages in accordance with the present invention are provided by a phased array antenna which may include a substrate, a plurality of phased array antenna elements carried by the substrate, and a central controller for providing beam steering commands and beam shaping commands. Furthermore, the phased array antenna may also include a plurality of element controllers connected to the phased array antenna elements and the central controller. Each element controller may store at least one position related value based upon physical positioning of the associated phased array antenna element on the substrate, and determine a beam shaping offset based upon the stored at least one position related value and a received beam shaping command from the central controller. Each element controller may also determine at least one phased array antenna element control value based upon a received beam steering command and the beam shaping offset.
More particularly, the plurality of phased array elements may be arranged in a predetermined pattern about a phase center, and the at least one position related value may be based upon physical positioning relative to the phase center. The central controller may provide common beam shaping commands to all of the element controllers, each of which may include a plurality of common beam shaping coefficients. Further, the at least one position related value may include a plurality of position related coefficients, and each element controller may determine the beam shaping offset based upon multiplications of the position related coefficients and the common beam shaping coefficients. Additionally, each element controller may further perform at least one accumulation.
Considered in other terms, each element controller may store, as the at least one position related value, a plurality of beam shaping offsets for respective different beam shapes. Moreover, each element controller may determine, as the beam shaping offset, one of the plurality of stored beam shaping offsets based upon receiving a corresponding beam shaping command therefor.
The central controller may provide the at least one position related value for storing in each element controller. The central controller may also determine the at least one position related value for storing in each element controller. Each element controller may include at least one register for storing the at least one position related value. In addition, the at least one phased array antenna element control value may include at least one of a phase and attenuation value.
A method aspect of the invention is for operating a phased array antenna such as that described above. The method may include storing, at each element controller, at least one position related value based upon physical positioning of the associated phased array antenna element on the substrate. Furthermore, at each element controller a beam shaping offset may be determined based upon the stored at least one position related value and a received beam shaping command from the central controller. The method may also include determining, at each element controller, at least one phased array antenna element control value based upon a received beam steering command and the beam shaping offset.